README web version of /home/usg/OPS/MTS/readme_xml/readme_75042400
Principal Investigator Email Address
Estimated Total Execution Time (hours, including overheads)
General Description
The massive HII region G333.6-0.2 is associated with a stellar
cluster that is so young that the winds from the massive stars have
not yet dispersed the gas in which they are embedded. With an
ionizing luminosity of 10^50 photons s^-1, it is an
extremely luminous HII region, but the source of the EUV radiation
remains enigmatic. With an estimated age of <10^4 yr, it is one
of the youngest nearby clusters, where dynamical evolution and
evolution of O-stars off the main sequence cannot yet have
occurred. The extremely high ionizing luminosity of the stars,
combined with the low excitation temperature of the gas require either
an unsual IMF or the modification of the SED of the stars via, e.g.,
accretion disk. We propose high-resolution NIR broad band imaging to
find the source of the ionizing photons. Additionally we want to
investigate the mass function of the cluster (and its spatial
variation) and examine the structure of the diffuse gas on small
scales.
Waiver Requests
Critical Observing Condition Constraints
Time-Critical Aspects
Special Execution Requirements
SKY MEASUREMENTS:
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G333.6-0.2 is embedded in diffuse extended emission of a few arcmin
size. For sky measurements we therefore added a
NACO_img_obs_GenericOffset template in all OBs in order to acquire
imaging of a region ~215" W and 35" S of the target. This region is
not entirely free of stars, but source density should be fairly low
and there is no diffuse emission (estimated from 2MASS image). Since
the offset is fairly large, the TIO may have to be informed to pick an
appropriate guiding star.
STRUCTURE of OBs:
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The general structure of the OBs is:
acquisition template
auto jitter short DIT
generic offset for sky measurement
auto jitter long DIT
generic offset for sky measurement
POSITIONING:
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The target, i.e. the dense core of G333.6-0.2, should be positioned in
the center of the detector (as shown on finding chart, where the S27
FOV is shown as a box around the core of the target). AutoJitter will
be used for the offsets.
GUIDING STAR/AO:
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No imaging at reasonably high resolution is available on
G333.6-0.2. We therefore had to rely on 2MASS/DSS data to prepare the
observations. The core of G333.6-0.2 (at 16:22:09.6 RA, -50:06:00 Dec)
appears extremely dense and cannot be separated into individual
sources on the 2MASS image (which was used to create the finding
chart). The suggested guiding star is located 8" to the south of the
core. It is listed as
a K = 8.5 source in 2MASS and as a V = 14.0 source in the guide star
catalogue 2. On DSS images the star stands out clearly as a single source.
Due to the limited information on the target we cannot
know a priori how well AO correction will work on the suggested
guiding stars.
We therefore prepared two sets of OBs and associated aocfg files. The
OBs are identical (except in DITs), but the guiding star/wavefrontsensor setup
is different. Of course, only ONE set of OBs is to be executed. The
decision depends on the night astronomer's success in locking the
AO. The OBs are organised in Subfolders "OBs_best" and "OBs_ok", with the corresponding
OBs also labelled with "best" and "ok".
1) The preferred OBs in the "OBs_best" subdirectory are to be tried first. There
are two
reference sources in the AO setup files. The night astronomer should try reference
star 1 first
and go to star 2 if necessary. The reference stars are at identical positions
and are marked as
"R best VIS/IR" in the corresponding finding charts. The only difference is the
WFS setup (VIS
in case 1 and IR in case2).
Names of OB associated aocfg file user priority
G333.6-0.2_K_imaging_best.obx G333.6-0.2.K.aocfg 1
G333.6-0.2_L_imaging_best.obx G333.6-0.2.L.aocfg 2
G333.6-0.2_H_imaging_best.obx G333.6-0.2.H.aocfg 3
G333.6-0.2_NB2.17_imaging_best.obx G333.6-0.2.NB217.aocfg 4
G333.6-0.2_NB2.12_imaging_best.obx G333.6-0.2.NB212.aocfg 5
G333.6-0.2_J_imaging_best.obx G333.6-0.2.J.aocfg 6
G333.6-0.2_M_imaging_best.obx G333.6-0.2.M.aocfg 7
2) In case the approach above does not work, we provide alternative OBs (with slightly
longer
DITs). These OBs are listed in the directory "OBs_ok". For the AO setup we
provide two reference stars
(at ~25" separation from the target) in the config file (listed in order of
preference).
Both stars are V = 13.4 and marked in the
corresponding finding charts as "R1 ok" and "R2 ok".
Names of OB associated aocfg file user priority
G333.6-0.2_K_imaging_ok.obx G333.6-0.2.K.ok.aocfg 1
G333.6-0.2_L_imaging_ok.obx G333.6-0.2.L.ok.aocfg 2
G333.6-0.2_H_imaging_ok.obx G333.6-0.2.H.ok.aocfg 3
G333.6-0.2_NB2.17_imaging_ok.obx G333.6-0.2.NB217.ok.aocfg 4
G333.6-0.2_NB2.12_imaging_ok.obx G333.6-0.2.NB212.ok.aocfg 5
G333.6-0.2_J_imaging_ok.obx G333.6-0.2.J.ok.aocfg 6
G333.6-0.2_M_imaging_ok.obx G333.6-0.2.M.ok.aocfg 7
Please note that the core of G333.6-0.2 appears extremely bright and
crowded on the 2MASS image (see finding chart). It may well be that a
bright NIR source suitable for guiding with the IR WFS is present in
the core. In this case, the night astronomer may select such a guiding
star and use the OBs listed under point 1).
Special Calibration Information
ToO Information
ToO Activators List
Is this a Pre-imaging run ?
Pre-imaging Requirements
Source(s) of Pre-imaging
Pre-imaging sources not listed above
Do all your OBs comply with the instrument-specific requirements listed
on the instrument-specific Phase 2 web page ?
If this is a pre-imaging run, did you select PRE-IMAGING for the Observing
Category for each Observing Template ?
Do all your finding charts comply with both the general and instrument-specific
Phase 2 Web Pages ?
If you submitted OBs for standard stars, did you specify the magnitude
and spectral type of all standard stars in the OBs ?
Have you included OBs for any calibrations that you need but which are
not part of the Calibration Plan ?
If you are observing Moving Targets, have you attached suitable ephemeris
files to your OBs?
If you have preferences which OBs should be executed first, did you make
use of the User Priority field in the OBs ?
If this is a run that requires coordinated observations with other facilities,
did you give proper instructions in the Time-Critical Aspects Section ?
If you have PSF reference star OBs, do the names of those OBs begin with
PSF_ ?
If there are Finding Charts attached to your OBs, is the field-of-view
of at least one of these charts 2' x 2' (with clearly labelled field orientation)
?
Have you clearly marked and labelled your wavefront reference objects
R1, R2, R3, ... (as specified in the NAOS Preparation Software) on your Finding
Charts ?
Have you specified the magnitude of the brightest object in the field-of-view
for each OB ?
Are there objects in any of your fields (including standard stars) which
are brighter than the limits specified in the User Manual and on NACO web Pages
?
If the previous answer is yes, have you given a list of OBs and a justification
for the brightness limit violation in the general description field ?
Last creation of page: Tue Oct 6 15:40:07 2009
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